Form 637

(Rev. December 2022)

Application for Registration 

(For Certain Excise Tax Activities)

Department of the Treasury 

Internal Revenue Service Go to www.irs.gov/Form637 for the latest information.

OMB No. 1545-1835

Part I Identification of Applicant Type or print 

Legal name of entity (or individual) for which the employer identification number (EIN) was secured Employer identification number (EIN) 

Trade name of business if different from above Telephone number 

Mailing address (number, street, and room or suite no.; if P.O. box, see instructions) Fax number 

City or town, state or province, country, and ZIP or foreign postal code 

If you listed a P.O. box above, or if your street address is different from your mailing address, list your street address (including city or town, state or province, country, 

and ZIP or foreign postal code) 

Part II Activities. Enter the activity letter from the chart on pages 2–5 and a brief description of each activity for which you’re 

applying for registration. Also, attach the Additional Information Required for each activity to which this application applies.

Activity Letter Activity Description 

Part III General Information 

Section A—For All Applicants 

Answer all the questions below. Attach a separate sheet(s), as needed, to answer lines 2b through 7. Identify each sheet with your 

name and employer identification number at the top, and write the number of the line to which each answer applies. If any questions 

don’t apply to you, explain why. 

1a Are you filing, or will you be required to file, Form 720, Quarterly Federal Excise Tax Return? . . . . . Yes No

b Have you previously applied to be registered by any IRS office? . . . . . . . . . . . . . . . Yes No

c Have you, or any related entity, had a Certificate of Registry or Letter of Registration revoked or suspended

by any IRS office? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No

d If you answered “Yes” to (b) or (c), enter the name of the IRS office 

2 a List the date your business started: Month Year 

b Explain in detail your business activity. 

3 For all other business entities to which you’re related, list: 

a The name and EIN of the related entity, 

b The percentage of ownership, and 

c How you are related (for example, stock, partnership, etc.). 

4 List all addresses of current business operations (include out-of-state or foreign operations, if applicable). 

5 List the address where your books and records are kept (if different from the address in Part I). 

6 List the names and taxpayer identification numbers (TINs) of all business owners, corporate officers, members, or partners. 

7 List the name and phone number of a person whom we can contact about this application. 

Section B—For All Fuel Applicants 

If you’re applying for fuel activities K, M, S, X, Y, AB, AF, AL, AM, CC, NB, QR, SA, SB, UA, UB, UP, or UV, you must complete line 8.

8 Describe any changes in your ownership or changes of controlling stock ownership in the past 2 years. If none, enter “None.” 

Also see Changes in Registration in the instructions. 

Go to Section C on Page 2 

For Privacy Act and Paperwork Reduction Act Notice, see instructions. Cat. No. 49952H Form 637 (Rev. 12-2022)
Form 637 (Rev. 12-2022) Page 2 

Section C—For Certain Fuel Applicants 

If you’re applying for fuel activities K, M, S, or Y, answer each question below by checking the “Yes” or “No” box. If you answer “Yes” 

to any of these questions, provide a full explanation. Attach additional sheets if needed. 

Have you or any related person (see Regulations section 48.4101-1(b)(5)) been:

9 Assessed any penalty under chapter 68 of the Internal Revenue Code (or similar provision of the law of any

state) for fraudulently failing to file any return or pay any tax, and the penalty hasn’t been wholly abated, 

refunded, or credited? . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No

10 Assessed any penalty under chapter 68 of the Internal Revenue Code, and the penalty hasn’t been wholly 

abated, refunded, or credited? . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No

11 Convicted of a crime under chapter 75 of the Internal Revenue Code (or similar provision of the law of any

state), or of conspiracy to commit such a crime, and the conviction hasn’t been wholly reversed by a court of

competent jurisdiction? . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No

12 Convicted, under the laws of the United States or any state, of a felony for which an element of the offense is 

theft, fraud, or the making of false statements, and the conviction hasn’t been wholly reversed by a court of

competent jurisdiction? . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No

13 Assessed any tax under section 4103 (willful failure to pay the tax imposed by section 4041(a)(1) or 4081) 

and the tax hasn’t been wholly abated, refunded, or credited? . . . . . . . . . . . . . . . Yes No

14 Advised that your registration has been revoked? . . . . . . . . . . . . . . . . . . . Yes No

Sign 

Here 

Under penalties of perjury, I declare that I have examined this application, and accompanying schedules and statements, and, to the best of my knowledge and 

belief, they are true, correct, and complete. 

Signature Title Date 

Type or print name below your signature. 

Activity Letter Additional Information Required 

A Manufacturer of gas guzzler 

automobiles, sport fishing equipment 

(including fishing rods and fishing poles), 

fishing tackle boxes, bows, quivers, 

broadheads, points, arrow shafts, 

taxable tires, or vaccines. 

1. List all articles you manufactured. Include advertising brochures, if available. 

2. List the organizations or businesses (for example, state or local government or school) to which 

you intend to sell articles tax free. 

3. List the monthly volume of tax-free articles you intend to sell. Also, list the monthly volume of 

taxed articles you intend to sell. 

B Buyer of sport fishing equipment 

(including fishing rods and fishing poles), 

fishing tackle boxes, gas guzzler 

automobiles, bows, quivers, 

broadheads, points, or vaccines for 

further manufacturing or for resale to a 

buyer for further manufacturing.

1. List articles you intend to purchase for further manufacturing or for resale for use by the buyer for 

further manufacturing. 

2. List the businesses that you will sell articles to for use in further manufacturing, if applicable. 

3. List your other types of sales of articles other than for further manufacturing. 

C Buyer of taxable tires for use on or in 

connection with the sale of another 

article the buyer manufactures and sells 

(1) for export, (2) to state and local 

governments, (3) to nonprofit 

educational organizations, or (4) as 

supplies for vessels or aircraft. 

1. List the type and weight of the tires you bought. 

2. List the articles you manufactured (a) on which the tires will be used, or (b) in connection with 

which the tires will be sold. 

3. List the organizations or businesses with which you intend to have tax-exempt sales. 

D Buyer with a place of business in the 

United States purchasing vaccines, gas 

guzzler automobiles, taxable tires, sport 

fishing equipment (including fishing rods 

and fishing poles), fishing tackle boxes, 

bows, quivers, broadheads, points, or 

arrow shafts for export or for resale to a 

second purchaser for export. 

1. List the articles you intend to buy for export or resale to others for export. 

2. List the businesses to which you intend to sell articles for export. 

E Buyer (other than state or local 

government) of gas guzzler automobiles 

for ambulance, law enforcement, or 

firefighting. 

Provide the general information for all applicants. 

Form 637 (Rev. 12-2022) 
Form 637 (Rev. 12-2022) Page 3 

Activity Letter Additional Information Required 

F Nonprofit educational organization, other 

than a public school, buying taxable 

tires, certain heavy vehicles, sport 

fishing equipment (including fishing rods 

and fishing poles), fishing tackle boxes, 

bows, quivers, broadheads, points, or 

arrow shafts for its exclusive use. 

1. Provide a general description of the type of your educational facility, including faculty, curriculum, 

and student body. 

2. Provide a copy of the IRS determination letter granting your exemption from federal income tax. 

3. List products subject to federal excise tax you bought for the exclusive use of your organization

and how the products will be used in the operation of your organization. 

4. List activities (other than educational) conducted by the organization. 

G Persons making inventory exchanges of 

taxable chemicals under section 

4662(c)(2) or persons selling or buying 

intermediate hydrocarbon streams under 

section 4662(b)(10). 

1. List the taxable chemicals you exchange. List the intermediate hydrocarbon streams you sell or 

buy. 

2. Describe your processing plants, products produced, handling and storage facilities, and 

processes involving hydrocarbon streams, if applicable.

I Buyer (other than nonprofit educational 

organization or state or local 

government) of taxable tires for use on 

certain intercity, local, or school buses. 

1. List types and weights of tires you bought. 

2. Describe the types of buses (intercity, local, or school) on which the tires are used. 

3. Describe how the buses are used in the operation of the business. 

K Buyer of kerosene for a feedstock 

purpose. 

List the type of kerosene you purchased, and describe the product and manufacturing process for 

which the kerosene will be used as a feedstock. 

M Blender of gasoline, diesel fuel 

(including a diesel-water fuel emulsion), 

or kerosene, producing a taxable fuel 

outside the bulk transfer/terminal 

system, including blenders of alcohol 

fuel mixtures, alternative fuel mixtures, 

biodiesel mixtures, and renewable 

diesel mixtures. 

1. List the products you bought or produced for blending with gasoline, diesel fuel, or kerosene. 

2. List the annual volume of products you bought for blending. 

3. List the annual volume of blended taxable fuel you produced. 

Q First retail seller of certain heavy 

vehicles. 

1. Describe the heavy vehicles you intend to sell. 

2. Describe the exempt sales of the heavy vehicles you intend to make. 

S Enterer, position holder, refiner, terminal 

operator, or throughputter of gasoline, 

diesel fuel (including a diesel-water fuel 

emulsion), or kerosene, or industrial user 

of gasoline. 

1. List the annual volume of gasoline, diesel fuel, and kerosene you entered into the United States or 

produced. 

2. List the locations and a description of your refineries, terminals, and pipelines. 

3. List the names and addresses of any person(s) who will be acting for you as an agent or broker in 

entering, buying, selling, or transporting any fuel. 

4. List the business entities to whom you sell and with which you buy, trade, transfer, or exchange 

any gasoline, diesel fuel, and kerosene. 

5. Provide the annual volume of gasoline, diesel fuel, and kerosene you buy, sell, trade, transfer, or 

exchange.

V Manufacturer, importer, or buyer of 

ozone-depleting chemicals (ODCs) for 

export. 

1. List the ODCs you import or manufacture for export. 

2. List the companies from which you buy ODCs for export. 

3. List the number of pounds for each type of ODC you exported in this calendar year and an 

estimate for next calendar year. 

4. List your export locations, and list your production allowance, consumption allowance, export 

allowance, and export percentage as set by the Environmental Protection Agency. 

X Pipeline operator or vessel operator 

(including certain deep-draft vessels) 

within the bulk transfer/terminal system. 

1. Schematic or map of your pipeline locations. 

2. Names and addresses of facilities served by your pipeline or vessel. 

3. Number, description, and capacities of your vessels used to transport taxable fuel. 

Y Buyer of kerosene for its use in 

commercial aviation (other than foreign 

trade). 

1. List the quantity, types, and gross take-off weights of all aircraft you own and/or operate. Include 

the countries of registration. Aircraft that you operate but that are owned by other persons should be 

clearly designated. Information should be included as to the operating arrangements. 

2. List the average number of operating hours (per month) of each aircraft that is listed in item 1. 

Show the number of hours for commercial aviation (other than foreign trade) and noncommercial

aviation. 

3. If you maintain kerosene storage facilities, list the location and capacity of each facility.

AB Producers and importers of 

agri-biodiesel. 

1. List the annual volume of agri-biodiesel you produced in or entered into the United States. 

2. List the locations and a description of your production facilities. 

3. List the names and addresses of any person(s) who will be acting for you as an agent or broker in 

entering, buying, selling, or transporting any agri-biodiesel. 

4. List the business entities to whom you sell and with which you buy, trade, transfer, or exchange 

any agri-biodiesel. 

5. Provide the annual volume of agri-biodiesel you buy, sell, trade, transfer, or exchange. 

AF Producers and importers of alcohol. 1. List the annual volume of alcohol you produced in or entered into the United States. 

2. List the locations and a description of your production facilities. 

3. List the names and addresses of any person(s) who will be acting for you as an agent or broker in 

entering, buying, selling, or transporting any alcohol. 

4. List the business entities to whom you sell and with which you buy, trade, transfer, or exchange 

any alcohol. 

5. Provide the annual volume of alcohol you buy, sell, trade, transfer, or exchange. 

Form 637 (Rev. 12-2022) 
Form 637 (Rev. 12-2022) Page 4 

Activity Letter Additional Information Required 

AL Alternative fueler that sells for use or 

uses alternative fuel as a fuel in a motor 

vehicle or motorboat. 

Provide the general information for all applicants. 

AM Alternative fueler that produces an 

alternative fuel mixture that is sold for 

use or used in the alternative fueler’s 

trade or business. 

Provide the general information for all applicants. 

BC Qualified blood collector organization 

buying taxable fuel, taxable tires, and 

certain heavy vehicles; claiming 

exemption from the communications 

tax and heavy highway vehicle use tax; 

or to claim a credit or payment of 

certain excise taxes, for its exclusive 

use in the collection, storage, or 

transportation of blood. 

1. Provide a general description of your blood collection activity. 

2. Provide a copy of the IRS determination letter granting you an exemption from federal income tax 

under section 501(a) as an organization described in section 501(c)(3). 

3. Provide evidence of your registration with the Food and Drug Administration as a blood collector. 

CC Credit card issuer that issues credit 

cards for sales of taxable fuel to a state 

or local government for its exclusive use 

or for sales of gasoline to a nonprofit 

educational organization for its exclusive 

use. 

Provide the general information for all applicants. 

NB Producers and importers of biodiesel 

(other than agri-biodiesel) and renewable 

diesel. 

1. List the annual volume of biodiesel and renewable diesel you produced in or entered into the

United States. 

2. List the locations and a description of your production facilities. 

3. List the names and addresses of any person(s) who will be acting for you as an agent or broker in 

entering, buying, selling, or transporting any biodiesel and renewable diesel. 

4. List the business entities to whom you sell and with which you buy, trade, transfer, or exchange 

any biodiesel and renewable diesel. 

5. Provide the annual volume of biodiesel and renewable diesel you buy, sell, trade, transfer, or 

exchange. 

QR Qualified retailer of diesel fuel or 

kerosene sold in Alaska for nontaxable 

uses. 

Provide the general information for all applicants. 

SA Producers or importers of sustainable 

aviation fuel.

1. List the annual volume of sustainable aviation fuel you produce. 

2. List the locations and a description of your production facilities. 

3. List the feedstocks and sources of feedstocks used to produce the sustainable aviation fuel. 

4. Provide a statement indicating whether you produce sustainable aviation fuel under an ASTM 

D7566 Annex or ASTM D1655 Annex A1, and, if applicable, the specific ASTM D7566 Annex under 

which the SAF synthetic blending component is produced. 

5. Provide a sample Certificate of Analysis for the type of sustainable aviation fuel you produce, 

demonstrating conformance with either an ASTM D7566 Annex or ASTM D1655 Annex A1. 

6. Provide certification from the International Sustainability and Carbon Certification (ISCC), 

Roundtable on Sustainable Biomaterials (RSB), or other unrelated party demonstrating compliance 

with (i) any general requirements, supply chain traceability requirements, and information transmission 

requirements established under CORSIA, which has been adopted by the ICAO with the agreement of 

the United States; or (ii) any similar methodology that satisfies the criteria under section 211(o)(1)(H) of 

the Clean Air Act (42 U.S.C. 7545(o)(1)(H)), as in effect on August 16, 2022. 

7. Provide certification in accordance with section 40B(e) that the SAF synthetic blending component 

has a lifecycle greenhouse gas emissions reduction percentage of at least 50%. 

8. List the names and addresses of any person(s) acting for you as an agent or broker in buying, 

selling, or transporting any sustainable aviation fuel. 

9. List the business entities to which you sell sustainable aviation fuel. 

10. List the business entities from or with which you buy, trade, transfer, or exchange any sustainable 

aviation fuel. 

11. List the annual volume of the sustainable aviation fuel you buy, sell, trade, transfer, or exchange. 

SB Producers of second generation 

biofuel. 

1. List the annual volume of cellulosic biofuel (including second generation biofuel) you produced in 

the United States. 

2. List the plant material you used to produce the cellulosic biofuel (including second generation 

biofuel). 

3. List the locations and a description of your production facilities. 

4. List the names and addresses of any person(s) who will be acting for you as an agent or broker in 

buying, selling, or transporting any cellulosic biofuel (including second generation biofuel). 

5. List the business entities to whom you sell and with which you buy, trade, transfer, or exchange 

any cellulosic biofuel (including second generation biofuel). 

6. Provide the annual volume of cellulosic biofuel (including second generation biofuel) you buy, sell, 

trade, transfer, or exchange. 

Form 637 (Rev. 12-2022) 
Form 637 (Rev. 12-2022) Page 5

Activity Letter Additional Information Required 

UA Ultimate vendor that sells kerosene for 

use in aviation. 

Provide the general information for all applicants. 

UB Ultimate vendor that sells undyed diesel 

fuel or undyed kerosene for use in 

certain intercity and local buses. 

Provide the general information for all applicants. 

UP Ultimate vendor that sells kerosene 

from a blocked pump. 

1. Describe the blocked pumps you used to sell kerosene in your business. 

2. List the location of your blocked pumps. 

UV Ultimate vendor that sells (a) undyed 

diesel fuel or undyed kerosene to a state 

or local government for its exclusive use, 

or (b) gasoline (including aviation 

gasoline) to a state or local government 

for its exclusive use or to a nonprofit 

educational organization for its exclusive 

use. 

Provide the general information for all applicants. 

Section references are to the Internal Revenue Code unless 

otherwise noted. 

Future Developments 

For the latest information about developments related to Form 

637 and its instructions, such as legislation enacted after they 

were published, go to www.irs.gov/Form637.

What’s New

Activity letter SA. The Inflation Reduction Act of 2022 enacted 

the section 40B sustainable aviation fuel credit for certain fuel 

mixtures containing sustainable aviation fuel sold or used after 

December 31, 2022. The IRS designated SA as the activity letter 

related to this credit. See Notice 2023-06.

Reminder

Reinstatement of activity letter G. The Infrastructure 

Investment and Jobs Act reinstates the excise taxes imposed 

on certain chemical substances by sections 4661 and 4671, 

effective July 1, 2022. Activity letter G is reinstated for persons 

making inventory exchanges of taxable chemicals under section 

4662(c)(2), or persons selling or buying intermediate 

hydrocarbon streams under section 4662(b)(10). See Notice 

2021-66, 2021-52 I.R.B. 901, available at www.irs.gov/

irb/2021-52_IRB#NOT-2021-66.

General Instructions 

Purpose of Form 

Use Form 637 to apply for excise tax registration for activities 

under sections 4101, 4222, 4662, and 4682. See the chart on 

pages 2–5 for the list of activities. Each business unit that has, 

or is required to have, a separate EIN is treated as a separate 

person. 

The following persons must be registered.

• Pipeline operator or vessel operator: activity letter X. 

• Enterers, position holders, refiners, and terminal operators: 

activity letter S. 

• Blenders: activity letter M. 

• Producers or importers of alcohol, agri-biodiesel, and 

biodiesel (including renewable diesel): activity letters AF, AB, 

and NB, respectively.

• Producers or importers of sustainable aviation fuel: activity 

letter SA.

• Producers of second generation biofuel: activity letter SB. 

Current CB registrants will not need to reapply for new SB

registrations.

Pub. 510, Excise Taxes, has more information regarding 

registrations. 

Penalty 

The penalty for failure to register, if you’re required to register, is 

$10,000 for the initial failure, and $1,000 for each day following 

that you fail to register. The penalty applies unless the failure to 

register is due to reasonable cause. 

How To Apply 

Complete Form 637 and submit it with the required additional 

information described on the chart on pages 2–5. You may use 

additional sheets for your explanations. Write your name and 

EIN on each sheet you attach. You must send all of the required 

information or the processing of your application will be 

delayed. The IRS will ask you for additional information if 

needed, or you may provide additional information at any time. 

The application must be reviewed and approved before you’re 

registered for any activity, and bond may be required. The 

review may include inspection of your premises during normal 

business hours without advance notice. If your application is 

approved, the IRS will issue a Letter of Registration. The letter 

will include the activities you’re registered for, the effective date 

of the registration, and your registration number. A copy of Form 

637 isn’t a Letter of Registration. If your application is denied, 

you will be notified by the IRS in writing, including the reason for 

the denial. 

Employer Identification Number (EIN) 

Enter your EIN. If you don’t have an EIN, you may apply for one 

online by visiting www.irs.gov/EIN. You may also apply for an 

EIN by faxing or mailing Form SS-4, Application for Employer 

Identification Number, to the IRS.

P.O. Box 

If the post office doesn’t deliver mail to your street address and 

you have a P.O. box, show the box number instead of the street 

address. 

Signature 

Form 637 must be signed by a person with authority to bind the 

applicant. 

The authority to bind means the ability to execute agreements 

that are binding and legally enforceable against the applicant 

under state law. Form 637 submitted by:

• An individual or sole proprietorship—must be signed by that 

individual;

• A partnership—must be signed by any one of the general 

partners;

Form 637 (Rev. 12-2022) 
Form 637 (Rev. 12-2022) Page 6 

• A limited liability company (LLC)—must be signed by a 

person that complies with the federal tax treatment of the LLC; 

if the LLC is taxed as a partnership, then Form 637 must be 

signed by a member manager of the LLC; if the LLC is taxed as 

a corporation, then the rules for corporations must be followed; 

• A corporation—must be signed by the president, vicepresident, treasurer, assistant treasurer, chief accounting 

officer, or any other officer duly authorized to act for the 

corporation; 

• A government agency—must be signed by any person legally 

authorized to act for the agency; 

• A tax-exempt organization—must be signed by any person 

legally authorized to act for the organization; if the organization 

is a corporation, the rules for corporations must be followed; if 

the entity is a trust or other type of entity, those rules must be 

followed; or

• An estate or trust—must be signed by a fiduciary or 

authorized representative. 

Where To Apply 

Fax Form 637 to 855-887-7735 or send to:

Department of the Treasury 

Internal Revenue Service 

Excise Operations Unit—Form 637 

Mail Stop 5701G 

Cincinnati, OH 45999

Changes in Registration 

If an IRS office has issued you a Certificate of Registry or a 

Letter of Registration that is still in effect for an activity, you 

don’t have to reapply for registration for that activity unless 

notified to do so. However, see Reregistration for fuel activities 

under section 4101, later. To confirm the status of a registration, 

visit https://apps.irs.gov/app/exciseTax/. To apply for another 

activity or to cancel a registration, you must contact the IRS 

office in which you’re registered.

Notify the IRS office within 10 days if any information 

submitted with an application changes. This includes, but isn’t 

limited to, address changes or changes in business activities. A 

registrant may not sell, lease, or otherwise allow another person 

to use its registration. 

Reregistration for fuel activities under section 4101. You 

must reregister with the IRS if there’s a change of more than 

50% of the ownership of a registrant. In this instance, a change 

in ownership means that after a transaction (or series of 

transactions), more than 50% of the ownership interests in, or 

assets of, a registrant are held by persons other than persons 

(or persons related thereto) who held more than 50% of such 

interests or assets before the transaction (or series of 

transactions). Reregistration doesn’t apply to companies whose 

stock is regularly traded on an established securities market. If 

you fail to reregister as required, see Penalty, earlier. 

To reregister, send a newly completed Form 637 to the 

address under Where To Apply, earlier. On line 1d, enter your 

current registration number. The IRS will revoke the current 

registration number and issue a new registration to the new 

ownership (registrant). 

Additional Registration Information 

For registration relating to: 

• Taxable fuel, see Regulations section 48.4101-1. 

• Taxable chemicals, see sections 4662(c)(2) and 4662(b)(10).

• Exports of ozone-depleting chemicals, see Regulations 

section 52.4682-5. 

• All other articles, see Regulations section 48.4222(a)-1. 

See the Instructions for Form 720 for a list of notices providing 

additional guidance.

Privacy Act and Paperwork Reduction Act Notice. We ask for 

the information on Form 637 to carry out the Internal Revenue 

laws of the United States. We need it to figure and collect the 

right amount of tax. Subtitle D of the Internal Revenue Code, 

Miscellaneous Excise Taxes, imposes certain excise taxes. 

Section 4101 requires certain persons to register for excise 

taxes on fuel, as imposed by sections 4041 and 4081. Sections 

4101, 4222, 4662, and 4682 allow certain other manufacturers, 

sellers, or purchasers to register to be eligible for credits or to 

be exempt from the excise tax on taxable articles. If you’re 

required to register under section 4101 or if you elect to register 

for credits and/or exemption, you’re required to provide the 

information requested on this form. Failure to provide this 

information may subject persons required to register to 

penalties, and may delay or prevent the processing of a 

voluntary registration for credits or exemption; providing false 

information may subject you to penalties. Section 6109 requires 

you to provide the requested identification numbers. 

You’re not required to provide the information requested on a 

form that is subject to the Paperwork Reduction Act unless the 

form displays a valid OMB control number. Books or records 

relating to a form or its instructions must be retained as long as 

their contents may become material in the administration of any 

Internal Revenue law. 

Generally, tax returns and return information are confidential, 

as required by section 6103. However, section 6103 allows or 

requires the IRS to disclose or give such information to the 

Department of Justice for civil and criminal litigation; to cities, 

states, the District of Columbia, and U.S. commonwealths and 

possessions to administer their tax laws; and to other countries 

under a tax treaty. We may also disclose this information to 

federal and state agencies to enforce federal nontax criminal 

laws, or to federal law enforcement and intelligence agencies to 

combat terrorism. 

The time needed to complete and file Form 637 will vary 

depending on individual circumstances. The estimated average 

time is: Recordkeeping, 7 hr., 39 min.; Learning about the law 

or the form, 1 hr., 37 min.; and Preparing and sending the 

form to the IRS, 4 hr., 13 min. 

If you have comments concerning the accuracy of these time 

estimates or suggestions for making Form 637 simpler, we’d be 

happy to hear from you. You can send us comments from 

www.irs.gov/FormComments. Or you can write to:

Internal Revenue Service 

Tax Forms and Publications 

1111 Constitution Ave. NW, IR-6526 

Washington, DC 20224

Don’t send Form 637 to this address. Instead, see Where To 

Apply, earlier.